This invention relates to a method and apparatus for hydraulically assembling a driven shaft to a driving member, and particularly to such a method and apparatus for detecting improper or incomplete assembly.
It is a conventional procedure to assemble or couple a driven shaft, such as a front axle of a frontwheel drive automotive vehicle, with a snap ring in a circumferential groove adjacent to one end, to a driving member by means of a hydraulic device. The end of the drive shaft is pressed by the hydraulic device into a mating socket portion of the driving member until the snap ring engages a groove provided at a specified axial location in the mating portion of the driving member, so that the ring will prevent the driven shaft from slipping out from the driving member.
In this procedure, occasionally the snap ring will be caught by an inlet portion of the driving member and will prevent the driven shaft from being inserted far enough into the driving member for the snap ring to engage the specified groove.
In a normal assembling operation, the driven shaft is moved to the predetermined assembled position by supplying a sufficient amount of oil to a cylinder of a hydraulic actuator at a sufficient pressure to slide the end of the shaft into the driving member. An overload may be imposed on the hydraulic actuator if the snap ring becomes caught by the inlet end of the driving member, or the hydraulic cylinder may otherwise be rendered inoperative due to some load variations.
Conventionally, correct assembly of the driven shaft into the driving member is determined by ascertaining that the stroke of the hydraulic actuator reaches a predetermined point. Some installations use a limit switch for measuring the stroke, or a stroke measuring unit such as a linear scale, for example. These additional devices are disadvantageous in that they require installation space, and the linear scale is expensive. Another disadvantage is that malfunctioning of the hydraulic actuator due to load variations is detected only indirectly, by way of measurement of the stroke of the actuator.
Where a shaft is pressed in against a stopper by means of a hydraulic actuator, an indication of abutting engagement between the shaft and the stopper is normally gained indirectly by measuring the stroke of the hydraulic actuator. It has been difficult to provide a direct indication which shows that the shaft has abutted against the stopper.